fun main() {
    val map = mapOf("jack" to 20, "jason" to 18, "jk" to 98)
//    mapOf(Pair("jimmy",20),Pair("jacky",20))
    println(map["jack"])
    println(map.getValue("jack"))
    println(map.getOrElse("rose"){"unknown"})
    println(map.getOrDefault("rose",0))

    map.forEach{
        println("${it.key}, ${it.value}")
    }

    map.forEach{(key:String, value:Int) ->
        println("$key, $value")
    }
}